GWS Spitfire Build thread (with glassing tutorial)

I originally wanted to do a glassing tutorial while repairing my corsair, and although the repairs turned out wonderfully, I felt it wasn't a good subject for a full fledged build and glassing thread.

So, as I wanted to build a spitfire anyway, and the LHS had the slope glider version on sale, I picked it up cheap (less than $50 CAD) and will use that as the basis for my build tutorial. This will be a powered version but I'll be using stock equipment (EDP350C with B gearing found in the powered version) that I have laying around. The power system comes from my Corsair which is being convered to Brushless.

As this is mostly a build thread and glassing tutorial, I'll be glossing over some of the minor details of building GWS specific models. If you've built more than one GWS model you'll know that the majority of their construction is the same accross their line.

Materials
- Poly Instafil lightweight spackling compound. This is available from HomeDepot, Rona, or pretty much any home supply store.
- 21 gram (.75 oz) weight fiberglass cloth purchased from hobby shop.
- Minwax, Ultra fast drying Polycrylic. I use cear semi-gloss but any colour will work.
- Various grits of sand paper from 150 to 400.

Model preparation.
Obviously GWS models are made of injection molded foam. The injection technique tends to leave marks and other imperfections on the parts. These need to be filled and sanded. The ejection pin marks are the round 'embosed' marks on the bottoms of the wings and tail surfaces. The fuselage also tends to have a large number of smaller pin marks.

Use the lightweight spackle to fill the larger pin marks. A plastic spatula or thin plastic sheet is used to level the spackle to the rest of the surface just as you would use it on the wall in your house. Let this dry overnight and then sand the whole surface down with 150 to 200 grit sandpaper. Don't worry if the GWS paint comes off (in fact it's better if it does come off).

Use a hot knife (I use a #11 blade mounted to the end of a soldering iron) to cut open the access for the 350C motor electrical cable.

Once that opening is complete, test fit the fuselage halfs together. Sand off as much paint as possible from the inner portions of the fuselage halfs to allow the foam cement (I use the GWS stuff from the kit) to hold properly.

Apply the cement thinly to both sides of the fuselage and wait 10 minutes. The cement should be just tacky to the touch. Then put the two halfs together. NOTE: You'll only get one shot at this. Waiting for the GWS glue to become tacky will not allow you to maneuver the parts once they're together. This however provides a much stronger bond than putting the parts together when the glue is still very wet. With the parts together press them firmly until you see a little bead of cement ooze up through the seams. Use masking tape to hold the parts together. Again, masking tape will take the GWS paint off the parts when you remove it, but as I'm repainting, it doesn't matter.

The GWS glue takes a few hours to cure. Once it's ready to be handled apply more lightweight spackle to the seams of the fuselage, any dents or bumps you see, and double check the ejection pin marks on the wing. Let the spackle cure overnight.

Sand all parts down with 150 to 200 paper. When sanding down the wings, pay special attention to the leading edge. During the part creation process thin slices of foam (called flash) are left behind. this is due to small amounts of foam squeezing inbetween the top and bottom parts of the steel mold as the foam is injected. The leading edge of the wing will work better in the air if it has a nice rounded surface to it. So remove the flash and sand the leading edge so it's rounded.

Next we're ready for our first go at fibreglassing.

Glassing.

At first glassing a model seems a little intimidating but really it's rather simple. And the fact we're using a slow drying polycrylic with no oder really helps. When I build my scale ship models I use fiberglass resin and man, that stuff really reaks.

Start with a simple part. The horizontal stab works well as it's the smallest, and simpliest part. I generally don't remove the control surfaces from the parts until after glassing. But that's intirely up to you. The layout of some control surface mechanics may make it easier to build the control surfaces before glassing (the ailerons on the Corsair for example).

Cut the glass sheet so that the material is slighly larger than the part. I generally try to keep with in 5CM of the outside of the part, following the contour. This gets tricky with the lightweight material as it doesn't cut very well.

Using a foam brush (foam doesn't leave hairs on the part), dribble the Polycrylic down the centre of the part lengthwise. Be liberal with it.

Brushing from the centreline outwards, spead the liquid out toward the edges. The fibre material will become transparent as the Polycrylic liquid soaks in. The material will also begin to adhere to the part.

The fuselage, with its compound curves, is more difficult, but if you take your time you will have few problems. One of the tricks for curves (especially wing edges) is to cut slits toward the part so that the glass fibre will fold around the part and overlap, rather than bunch up.

For the sake of it being easier, I generally do one half of each part at a time. Bottom portion of the wing and one half of the fuselage one day. Then the remaining sides and halfs the next day. As this is still the first coat of PolyCrylic no noticable ridges will be seen in the model and it makes for much easier handling.

Although the label on the can of Polycrylic states that it takes 2 hours to dry, I have found that 2 hours makes it dry to the touch, but not for sanding. I generally let each coat of Polycrylic dry 5 to 10 hours.

Images

Once the first coat is dry the next step is to trim the wings and tail surfaces. Although we took steps to ensure nice round edges for the leading edge of the wing, trailing edges and portions of the tail may not be perfect.

Here is a little trick. Trim the remainder material off as close to the part as you can. Then set a basic house hold iron to low heat (no steam). Press and roll the edges of the part against the iron. This will press the material into the foam and seal it. This takes a bit of practice but it's best to start with low heat and old the part there until the material sets, than to start with high heat and risk melting everything.

Note, you probably want to use an iron you're not planning on useing on clothing anymore. Otherwise you could find yourself sleeping in your workshop if your wife uses the iron that is covered in traces of polycrylic.

All major parts trimmed, sanded, and ready for their second coat of Polycrylic.

This is a good time to add second areas of fibreglass cloth. I have found that the weakest point of most GWS warbirds is the section of fuselage right behind the wing and cockpit. It's a good idea to add a second small piece of fibre cloth to this area while adding the next coat of Polycrylic. It adds a small amout of weight but it's a stronger plane and can take more abuse.

Images

Well, as the second coat of Polycrylic dries, it's a good time to figure out what colour scheme is going on the model.

The supplied markings (DW-0) were used by the Royal Auxilliary Air Force's 610 "County of Chester" Squadron. The markings, from what my research shows, are more or less accurate. Going strickly scale (and I try to as much as possible), the fuselage roundel is too small as are the wing top roundels. At least the kit comes with two sizes for the wing roundels and, if planning to build the kit squadron, you should use the larger ones. The kit camoflage tries to represent RAF Early Day Scheme 'B'. The colours should be sky grey underside, Dark Earth and Dark Green topside. The pattern is more or less correct but for more accuracy you should base your pattern on this diagram. It's the most accurate for that scheme I've found.

So that's the kit markings out of the way.

My colour scheme and unit markings are going to be RCAF (as are the majority of my model subjects)

I have chosen the RAF Late Day Scheme 'A' with grey and green. The painting diagram can be seen here; click me

During WWII there was little distinction between RAF and RCAF markings on aircraft. Spitfires however carried a small roundel under the cockpit windscreen that is the familiar blue circle with the red maple leaf in it. It was the basis for the modern RCAF/CAF roundel. Canada was the first commonwealth nation to put its own flair to aircraft roundels to differentiate it from British aircraft. I expect the model to resemble this when completed;

Well, 3 coats of Polycrylic later and we're ready for the final sanding. I generally give the whole model a light sanding with 200 grit sandpaper to get the larger bumps down, then I use wet 400 grit to give me a smooth finish. The wet paper will cause the polycrylic to turn slightly blue again, but that will go clear when it's dry.

Now we can get back to the actual model construction. Use your hot knife and a steel ruler to cut the control surfaces off the model. Again, you can use a basic house hold iron set on low heat to seal the areas cut by the knife. Pressing and rolling the inner end of the rudder for example will seal the glass and foam together where they've been cut.

Images

From here on in, we're pretty much back to the kit instructions. I'll go into less detail now until at the painting stages.

The images below show the control surfaces after they've been built onto the model using the instruction desribed method.

In hind site, I would have fixed the top access hatch (battery and RC cover) to the model before glassing it. And cut it out of the model after the glassing process finished. As it stands now, unfortunately the access hatch doesn't quite fit properly leaving an unslightly seam where the two parts meet. Oh well, next time.

The model should come in at about the 450grams range. I used 3 coats simply to get the desired surface. 2 coats simply doesn't give a smooth enough finish for my tastes. And it's not like I plaster on the 2nd or 3rd coats. The 1st is pretty thick, but subsequint coats are very thinly applied then almost sanded off completely.

I'm considering a brushless for this after the build thread is complete but for the sake of the thread I'll use the stock equipment.

I start with the unpainted bird and sand carfully in one direction. I use the super light weight spackle stuff to fill in every dent and ding and mold marks. I start with 220grit and then finally to 400 and then 600 grit.

I use .5oz cloth (usually) although .75 is OK. I use very light coats of WBPU - even on the first coat. I can't tell how much you are using as mine are usually raw white foam and I can't see the white like you can. But I use just enough on the first coat to barely saturate the cloth.

I sand only after 24 hours of drying. I use the 220 careful to just start raising the hairs on the fiber. I do another coat, as thin as I can. Sand after 24hours. Then another coat sand with 400 grit, then a super light coat and final sanding with 600.

I don't wrap the cloth over the TE of the surfaces. Make sure they get plenty of WBPU to seal the foam.

Make sure the WBPU goes past the surface being covered then the sandpaper cuts right through it (no knife cutting necessary!). This is due to the overlapped WBPU that is now dry allowing the sandpaper to cut it...

So I use 4 coats of WBPU - all as thin as possible. In my GWS spit I added just shy of 2oz. Not too bad.